I wouldn’t charge those past 5 or 10 mA. I only have one charger that I might trust with them, and it’s a custom-made board from CRX that he shipped with a pair of 10250 cells. Even that is probably too high.
If I’m remembering right, there’s a couple of Micro-USB charging circuits that you can configure the charging current (I think that’s what CRX did) with resistor choice or something. Someone more knowledgeable than me will have to chime in, though.
Such button cells are made? Capacity must be very small. Are they worth it?
Seems if they do make them, there should be an appropriate charging device for them.
Honestly speaking, coin cells can be bought for affordable money if ordering in packs from China, or even from my own country or some nearby one. This is what I do. Buying them at local shops usually is noticeably more expensive.
If you have coin cell devices with high power consumption (?), rechargeables may be the way to go. Chargers for coin cells and other small batteries can be found. Can't comment about their overall quality, but in my experience they at least usually work fine enough.
Overall the reviews seem so-so. If the internal construction in those is too bad, the electronics inside their frames could be replaced with something better. TP4056 modules resistor modified for sufficiently low charging currents would be a very good choice.
The tough bit with coin cells is the marked difference between Panasonic’s coin cells and everybody else’s. At a previous job, I dealt with very high numbers of coin cells, of all varieties of quality. “Made in Japan” stood out from the rest.
Now, if you can find them cheap enough, $/Wh may be better from China. But for a lot of coin cell devices, changing them is a bother.
There are many other japanese manufacturers who make high quality cells, like Murata/Sony or Maxell. Last time I bought a 10-pack of Maxell branded CR2032s, the usual brand I get, on a small sale for less than $4 including shipping. I doubt there's much of a quality difference between any of the big brands.
On the other hand, I once dared to pay less than $0.75 for 5-packs of TianQiu branded cells on eBay. Ugh! I must admit those cells worked, but a lot less than expected. :facepalm: